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Results for “Impact phenomena”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1963

IMPACT PHENOMENA

Results of hypervelocity impact tests are analyzed, determining the penetration depth and time as a function of impact velocity

IMPACT TEST↗
DOE OSTI2024

Short-Run Marginal Emission Factors Neglect Impactful Phenomena and are Unsuitable for Assessing the Power Sector Emissions Impacts of Hydrogen Electrolysis

This comment reacts to Ruhnau and Schiele's (2023) assessment of the cost and emissions impacts of electrolytic hydrogen production operating under different green hydrogen certification requirements in the EU. We critique the paper's use of short-run marginal emissions rates to estimate emissions impacts, a methodology which the literature has shown to be inadequate for assessing the full lifecycle emissions impacts of electricity sector interventions. We hope that our response clarifies the need to consider induced structural change when assessing the greenhouse gas emissions impacts of electricity sector decisions at all scales.

electricity↗
NASA NTRS1988

Further investigations of oblique hypervelocity impact phenomena

The results of a continuing investigation of the phenomena associated with the oblique hypervelocity impact of spherical projectiles onto multi-sheet aluminum structures are described. A series of equations that quantitatively describes these phenomena is obtained through a regression of experimental data. These equations characterize observed ricoshet and penetration damage phenomena in a multi-sheet structure as functions of the geometric parameters of the structure and the diameter, obliquity, and velocity of the impacting projectile. Crater damage observed on the ricochet witness plates is used to determine the sizes and speeds of the ricochet debris particles that caused the damage. It is shown that, in general, the most damaging ricochet debris particle is approximately 0.25 cm (0.10 in) in diameter and travels at the speed of approximately 2.1 km/sec (6,890 ft/sec). The equations necessary for the design of shielding panels that will protect external systems from such ricochet debris damage are also developed. The dimensions of these shielding panels are shown to be strongly dependent on their inclination and on their circumferential distribution around the spacecraft. It is concluded that obliquity effects of high-speed impacts must be considered in the design of any structure exposed to the meteoroid and space debris environment.

Schonberg, William P.↗
NASA NTRS1988

Analysis of oblique hypervelocity impact phenomena

This paper describes the results of an experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectiles on multisheet aluminum structures. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to a meteoroid or space debris environement.

Schonberg, William P.↗
NASA NTRS1984

Impact phenomena as factors in the evolution of the Earth

It is estimated that 30 to 200 large impact basins could have been formed on the early Earth. These large impacts may have resulted in extensive volcanism and enhanced endogenic geologic activity over large areas. Initial modelling of the thermal and subsidence history of large terrestrial basins indicates that they created geologic and thermal anomalies which lasted for geologically significant times. The role of large-scale impact in the biological evolution of the Earth has been highlighted by the discovery of siderophile anomalies at the Cretaceous-Tertiary boundary and associated with North American microtektites. Although in neither case has an associated crater been identified, the observations are consistent with the deposition of projectile-contaminated high-speed ejecta from major impact events. Consideration of impact processes reveals a number of mechanisms by which large-scale impact may induce extinctions.

Grieve, R. A. F.↗
NASA NTRS1972

Preliminary examination of Surveyor 3 components for impact phenomena

Two pieces of the Surveyor 3 spacecraft recovered during the Apollo 12 mission were examined for secondary lunar ejecta and micrometeorite impacts. One piece was section E of the aluminum strut; the other was the nickel-coated beryllium television camera mirror.

Hallgren, D. S.↗
NASA NTRS1977

Low-speed impact phenomena and orbital resonances in the moon- and planet-building process

A simulation of collisional and gravitational interaction in the early solar system generates planets approximately 1000 km in diameter from an initial swarm of kilometer sized planetesimals. The model treats collisions according to experimental and theoretical impact results (such as rebound, cratering, and catastrophic fragmentation) for a variety of materials whose parameters span plausible values for early solid objects. The small planets form in approximately 1000 yr, during which time most of the mass of the system continues to reside in particles near the original size. The simulation is terminated when the largest objects' random motion is of smaller dimension than their collision cross-sections. The few 1000 km planets may act as seeds for the subsequent, gradual, accretional growth into full-sized planets.

Chapman, C. R.↗
NASA NTRS1984

Analyses of quasi-isotropic composite plates under quasi-static point loads simulating low-velocity impact phenomena

In thin composite laminates, the first level of visible damage occurs in the back face and is called back face spalling. A plate-membrane coupling model, and a finite element model to analyze the large deformation behavior of eight-ply quasi-isotropic circular composite plates under impact type point loads are developed. The back face spalling phenomenon in thin composite plates is explained by using the plate-membrane coupling model and the finite element model in conjunction with the fracture mechanics principles. The experimental results verifying these models are presented. Several conclusions concerning the deformation behavior are reached and discussed in detail.

Kelkar, A. D.↗
DOE OSTI2020

How Collective Phenomena Impact CO 2 Reactivity and Speciation in Different Media

CO 2 has attracted considerable attention in the recent years due to its role in the greenhouse effect and environmental management. While its reaction with water has been studied extensively, the same cannot be said for reactivity in supercritical CO 2 phase, where the conjugate acid/base equilibria proceed through different mechanisms and activation barriers. Furthermore, in spite of the apparent simplicity of the CO 2 + H 2 O reaction, the collective effect of different environments has drastic influence on the free energy profile. Enhanced sampling techniques and well-tailored collective variables provide a detailed picture of the enthalpic and entropic drivers underscoring the differences in the formation mechanism of carbonic acid in the gas, aqueous and supercritical CO 2 phases.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗